Television system



Jam, 5, 1943. A. N. GOLDSMITH gfiwgzw TELEVISION SYSTEM Filed Nov. 50,1940 2 Sheets-Sheet 1 iNVENTOR ATITCRNEY Jan. 5, 1943. A. N. GOLDSMRTHTELEVISION SYSTEM 2 Sheets-Sheet 2 Filed Nov. 50, 1940 INVENTOR ATTORNEYPatented Jan. 1943 UNITED STATES PATENT OFFICE" mavfs'ilffiam AlfredN.'Goldsmlth, New York, N. Y.

This invention relates to television systems and particularly to the.receiver end of such systems.

Primarily the invention is directed to a television receiver systemutilizing anamorphosis by which changes in the form or relativeproportions or aspect ratio of the television pictures or elecso thatthe aspect ratio or icture width to picture height were other than thesuggested .4 to 3 tro-optical images, as well as the electrical and theoptical processes therewith associated, are achieved.

In television receiver systems, as now customarily used, theelectro-optical representation which is to be viewed directly, orthrough appropriately arranged optical enlarging systems, or in suitableviewingreflectors, is formed electronically from a series ofsubstantially parallel lines produced by causing an intensity controlledcathode ray beam to traverse the luminescent target area of the cathoderay tube, In television systems recently used, such electro-opticalrepresentations usually result from tracing a,

cathode ray beam of substantially circular crosssection across theluminescent target area of a cathode ray tubein substantially parallelline traces, with the image formed from 441 line traces repeated thirty'times per second. Such repetition rate is suflicient for the observer tosense continuity of image reproduction upon the viewing target becauseof optical persistence of vision. The produced images usually have anaspect ratio of such an order that the width of the resultingelectro-optical image viewed on the end of the viewing tube has anaspect ratio' or a width-to-height relationship of the order of 4 to 3.Thus, for instance, if the cathode ray tube upon which theelectro-optical image is to be produced has a circular luminescenttarget' area or end portion of the order of 12" in diameter, the size ofthe optical representation which is created by the impact of the cathoderay beam upon the viewing target will be approximately reduced if itwere possible to produc a television image on the tube in such mannerthat at least one of the above suggested dimensions, preferablytheheight, as it is'viewed, because it affects the depth of the cabinet,could be reduced 55 ratio, and yet provision could be made for enablingan observer to view the actual television image in the desired 4 to 3aspect ratio.

Accordingly, it is an object of theinvention herein to be described toprovide a suitable system for compressing the television image in atleast one of its two dimensions, and preferably its height as viewed, soas to enable the utilization of television receiver cabinets which areshallower from front to back than would be required if such televisionpictures had normal proportions prior to actual viewing.

It is also an object of this invention to provide cathode ray imageproducing tubes for television use, wherein a cross-section of at leastthe larger portions of the tube maybe elliptical in nature, so that forthe production of a television image of a certain predetermined maxi-,

mum dimension, the tube will be shallower in the dimension perpendicularto the selected maximum than would be the case with the usual circularand conical construction of the flare of the image reproducing tube.

It is also an object of this invention to provide a television receivingand viewing arrangement for installation in a television receivercabinet which will substantially reduce thespace requirements fortelevision apparatus and make possible greater ease in handlingandshipping.

Another object of this invention is to provide a construction for-atelevision receiver arrangement which may readily be adapted to systemsutilizing either electro-static or electro-magnetic systems ofdeflection which shall function to distort the image in its initialproduction of the luminescent target of the cathode ray tube, so

that the image resulting is compressed in at least one of its twodimensions in order to enable the use of a shallower television receivercabinet.

:Another object of this invention is to provide a scanning cathode raybeam of elliptical crosssection capable of forming an ellipticalscanning 'spot on the luminescent target or screen, the

eccentricity of the ellipse being suited to the production of full andnormal detail in the anamorphotic image.

It is a still further object of this invention to carry on the reverseanamorphosis oi the luminescent target image by optical reflecting orrefracting means, so that the aspect ratio of the originally scannedfield shall be restored in the picture image which is finally viewed,irrespective of the fact that electrical or mechanical means aspectratio.

hereinbefore named.

It is another object of this invention-to provide a television systemand a viewing tube for viewing the television images where thetubetarget area is reduced so thattheiorce exerted on the end of thetube by air pressure is reduced, and consequently, the tube is less"'subject to implo sions.

It is a further object of this invention to provide an optical systemsuitable for producing en largements of the television images where theenlargement is different in each or twg directions because ofthe factthat an image "bfone aspect ratio is viewed as an enlargement'ih'adiilerent In this way the invention provides for enlarging anamorphotictelevision images so as to obtain a predetermined aspect ratio in thefinal image tobe viewed by the observer where the original image wasdeveloped with an aspect ratio diflerent from that originally viewed.

Other and further objectives will become apparent and at once suggestthemselves to those skilled in the art to whichf'the invention isdirected by reading the following specification in connection with theaccompanying. drawings, wherein Fig. 1 illustrates schematically a yokeconstruction for use with cathode ray image producing tubes "to providefor producing a distorted image in one direction. Fig. 2 represents inschematic form an electron gun for use in connection with a tube of thetype shown by Fig. l.

Fig. 3 represents in schematic form the pattern traced on the targetof'the tube of Fig. 2', when there is incorporated with the arrangementof Fig. 2 a yoke construction of the type shown, for example, by Fig. 1,or its equivalent. Fig. 3 serves to illustrate schematically theelectrical anamorphosis for compression of the picture or image beingcreated on the viewing target of the tube. Fig. 4 illustrates one methodof reversing the compression oi the image so as to expand the observableimage in one direction only. Fig. 5 illustrates schematically analternative optical modification of the arrangement oi Fig. 4. Fig. 6schematically illustrates, by way of elementary diagrammaticrepresentation, the manner in.

which the image produced on the luminescent target of the imagereproducing tube may be enlarged or expanded in one direction, forexample, in height. Fig. 7a illustrates in cross-section an opticalsystem for enlarging anamorphotic television images. Related Fig. 7b isa cross-section of the optical system of Fig. 7a taken in a direction at90 degrees to the showing of Fig. 7a.

Now referring, for example, to the drawings, for a further understanding01' this invention, it is to be understood that television (video orimage or picture) signals combined with synchro nizing signals, as isnow well known in the art. may be received from any transmittingstation. The signals are'received, detected, amplified, and

the synchronizing and controlling signals are separated trom the pictureor video signals. Separated synchronizi ig or control signals which areto be used for purposes of controlling the vertical deflection, thehorizontal deflection and for other incidental controls, are thenseparated from each other after the initial separation from the pictureor video signals.

One suitable form of receiver for accomplishing the foregoing result hasbeen claimed and described in the Carlson U. S. Patent Reissue No. I20,700, dated April 19, 1938; but it is to bq un- 75 derstood thatvarious other terms or receiver instrumentalities may be utilized wheredesired.

The present invention does not contemplate or require an special form ofreceiving circuit and is thereioreflexibly applicable to substantiallyany normal television receiving circuit or system.

In any event, a television system for reproducing pictures will beassumed to embody apparatus wherein picture signals are received fromany suitable form of transmitter, and after suitable amplification anddetection, utilized in any appropriate manner to control the intensityof the luminescent efiects observable on the viewing target of thecathode ray tube. Many and various eiiects for controlling the intensityoi the observable effects are known, included among which are theso-called grid modulation schemes, velocity modulation schemes, beamsize control schemes and various combinations oi the, forgoing. v

The specific means to produce. electro-optical effects upon the viewingtarget of the'cathcde ray image producing tube iormsno specific part oithis invention, only in so far as to become a part of the completesystem in order to utilize the effect of suitable modulation on theviewing target by the cathode ray tube, it being understood thatmodulation here refers to all forms or" intensity control aboveidentified. There is customarily provided for any television system asuitable deflecting means tor causing the developed beam to traverse theluminescent screen according to a bidirectional pattern of traversal.Such a pattern'is initially formed by directing the beam back and forthrather rapidly in a transverse path relative to the luminescent target,and si= multaneously to subject the developed cathode ray am to adeflection across the luminescent viewing target in a direction normalto the first direction. or deflection but operating at a much slowerrate than the first deflection. For instance, it be assumed thatpictures are being reproduced so as to form thirty d ll-line pic turesper second, but interlaced at two picture fields per picture frame, itcan be appreciated that the vertical deflection, that is, the slower ofthe two deflections. operates times per second, whereas the horizontaldeflection, thatis, the more rapid of per second.

In order to control the deflection oithe cathode ray beam developedwithin the cathode ray tube, an elliptical yoke i for providing magneticdeflection of the electron stream or beam is prefmeans are broughtsuitably close to the circular" cross-section of the cathode ray tubeand provided the strengths of the two mutually perpendicular deflectingfields are appropriate and adequate to produce the desired vertical andhorizontal deflections in the chosen anamorphotic relationship.

To deflect the electron beam in one of its two directions of deflection,there are provided pole pieces 2 and 3 about which are suitablypositioned deflecting coils 4 and 6, preferably connected in series bymeans of a conductor I, which 'hasthe and terminals 6 and 8 energizedfrom a suitable source of energy to produce a substantially sawtoothcurrent wave across the deflecting coils.

the two, operates at 13,230 times To deflect the cathode ray beamproduced within the tube in'a direction perpendicular to the preceding,there is a second set of coils 9 and 10 positioned about pole piecessimilar to the pole pieces 2 and 3. Energy is'supplied to the lastmounted on the same yoke, or the coils may be mounted upon separateyokes, depending upon the reaction taking place between the vertical andthe horizontal deflecting coils. In any case,

matically by Fig. 1, embrace a portion of the oathode ray imagereproducing tube I! through which the electron beam 30 passes after ithas been pro- Jected beyond the termination of the electron gun fromwhich it emanates (see Fi 2).

The cross-sectional area of the cathode ray scanning beam, as it isprojected through the cathode ray image producing tube and subjectand IDon the one. hand, and 4 and 5 on the other hand, may be ning lines, andalso parallel to the directionin which the resultant image is notcompressed;

the assembly of the yokes, which are shown scheed to the influence ofthe deflecting coils, and

thereafter, is preferably elliptical. Such an elliptical cross-sectionbeam canbe produced in a way which will be apparent from the gunconstruction shown by way of example in Fig. 2.

In Fig. 2 there is represented a rather conventional illustration of acathode ray tube l4, having a neck portion I40, in which is supported anelectron gun formed 'from a suitable electron emitter, one or moreaccelerator electrodes, and such control and shielding electrodes as maybe desired. In accordance with the applied modulation signals thecathode ray beam developed is caused to control the intensity of theluminescent effects resulting at the tube viewing target in accordancewith the intensity or time of impact or the density per unit area oftheimpacting electrons.

Because of the fact that the image produced is distorted or compressedin one of its two directions during its initial production on theluminescent target of the tube, the cross-section of the cathode raybeam as it, impinges upon the target also is preferably non-circular andhas an elliptical configuration, as will herein be explained.

In referring now, for instance, to Fig. 2 of the drawings, there iscontained within the neck Hit of the tube I4 a cathode element 22 whichmay be of the directly heated or indirectly heated type,

and. to which electrical connections maybe made at the terminal point2|. When the cathode member 22 becomes heated, electrons are driven offand caused to flow through the tube under the influence of anyaccelerating fields.

Closely adjacent the cathode, according to known construction, thecontrol electrode 24 is positioned. Control voltages, as determined byreceived signals, may be applied to the control electrode by way of theterminal connection 23. A first anode element 25,. havinga beam definingaperture 26, is then aligned with a similar aperture24a of the controlelectrode 24. Suitable operating and accelerating voltages are applied(from a voltage source not shown) to the anode by way of the terminalconnection 28. The aperture 26 is preferably elliptical'in nature, so asto restrict the electron flow through theanode to a cross-sectionalformation which is elliptical in nature, with the major axis of theellipseparallel to the more rapid path of deflection of the oathode raybeam as it traverses the luminescent target 21 of the tube, that is,parallel to the scan- Under such circumstances, the major axis or theelliptical aperture 26 isof'a length which cointhe developed cathode raybeam, conventionally represented at 30, after the beam has beendeflected, there is provided a second accelerating electrode 3| to whichpositive voltages may be applied (from a source not shown) by way of theterminal connection schematically represented at 32.

By the use of the elliptical scanning spot herein described, the fullpicture detail or resolution. is maintained along the scanning lines andalso perpendicular thereto. Furthermore the scanned field or raster issmooth, that is, without visible overlap or gaps between adjacentscanning lines. The diaphragm 29, included as a part of the first anode25, preferably has an aperture opening which is substantially largerthan that of the aperture 26, but the diaphragm serves to preventinteraction of disturbing fields upon the beam formation asit enters thefirst anode.

The deflecting system conventionally represented by Fig. 1 ispreferablypositioned about the neck Ila of the tube in a region intermediate thefirst anode 25 and the accelerating anode 3|, or, where a tube of suchhigh sensitivity .is not required or where greater power to deflect thebeam is available, the deflecting system of Fig. 1 may be located aboutthe neck of the tube intermediate the second accelerating anode 3| andthe target 21. When the deflecting system of Fig. l and the electrodeassembly schematically represented by Fig. 2 are utilized for producinga cathode ray beam, and sweeping that cathode ray beam across theluminescent target area 21,- the image pattern or raster traced upon thetarget may be conventionally represented by the raster pattern shown inFig.

3 by the shaded lines 4| included within the scanning spot 42 serving torepresent in this pattions of the cathode ray beam with the individualline traces of the raster being indicated by the lines From theforegoing it can be seen that if signals are received in a televisionreceiver of the character hereinabove referred to, and these signals areutilized to apply modulating voltages to ,the control electrode 24 .byway of suitable connections to the terminal 23, and if the beam isdeflected across the target 21 by a suitable deflecting system (forexample that of Fig. 1) there will result-on the viewing target 21 apattern which has one of its two dimensions, for example the dimensionAB, undistorted and the to its original proportions.

either be viewed directly or, if preferred, through a plane mirrormounted in the receiver cabinet other of its two dimensions, for examplethe dimension BC, substantially changed or distorted, so that theobserver viewing the target area 21 withoutthe benefit of suitable meansto restore the image to its true proportions would not see a truelikeness of the fleld of view scanned at the-point of transmission toproduce the signals which are applied as modulations to the controlelectrode 24. It is herein to be understood that the distortion abovementioned is not a distortion of outline but rather of aspect ratio.

herefore, in order to reverse the compression in question, there isprovided in association with the tube l4 and the viewed target 2'! asuitable optical system by which the image area ABCD may be expanded inat least one of its dimensions, that is, in the directions correspondingto the directions AD and BC, so as to transform the raster or patterninto a configuration of rectangular shape whose dimensions AB and BCshall be in the relation of 4 to 3, it being assumed that the desiredaspect ratio of the viewed image is 4 to 3. At the same time, theexpansion would,-in effect, restore the scanning spot to its intendedcircular cross-section.

To accomplish this purpose'in one way, there is placed at an appropriatedistance from the end 2] of tube I 4 upon which the image appears acylindrical lens element 51, having dimensions adequate to cover theentire picture producing area of the tube, as shown, and with itsdirectrices perpendicular to the direction of previous anamorphoticcompression of the picture image during its electrical production. Itcan be appreciated at once that a cylindrical lens of such characterwill not change the dimensions of the picture along the horizontal linesbut will visibly enlarge the dimensions of the picture along verticallines, which was above stated to be one oi the objects of the invention.By suitably selecting the index of refraction and the curvature of thecylindrical lens element 51, the picture area ABCD willappearto thelocker to be restored Such a picture may and tilted to an angle ofapproximately 45 degrees to the line of sight of'the looker. Under suchcircumstances, the tube II is positioned vertically in the receivercabinet and so mounted that the locker views normally a pictureundistorted along the horizontal lines but distorted vertically. Thereflecting mirror may be of the general type shown and claimed in U. S.Patent No. 1,870,702, granted to V. K. Zworykin on August 9, 1932. v

With, such an arrangement, if it be assumed that the lens 5'! be mountedfairly closely adjacent the luminescent target 21 of the tube l4, sothat the produced image in the direction between points B andC orbetween Aand D of Fig. 4; is within the boundaries of the same letterson Fig. 5, it will be appreciated that the light from the point C, forinstance, will follow the path indicated between point 93 through M to85. Also, it is apparent that there will be a path of light, forinstance, between point C and the central point 98 of the lens 51 whichemerges along the path 91. Consequently, since a similar effect takesplace from the point B, an observerwlll view through the lens 51 avirtual image between thev points B and C which is an enlargement ofline BC to the desired degree asindicated.

aaoaaxo .only two of all the existinglight-pathshave been Under suchcircumstances, it will be apprech ated at once that the point 95represents the principal focus of the cylindrical lens at the point andin theplane indicated, and thatrthe light wave at the point C, or point93, which passes through the optical center or optical con t-raldirection of the lens at 96, will continue on its way undefiected alongthe path 91. The other ray from the point C or 93, which is parallel tothe optical axis of the lens will, after passage through the lens, passthrough the focus 95 along the path between 34 and 95. Thus, if the raysare projected backward, it will be evident that a virtual image isformed, and to an observer the image of the line BC appears to be backand farther away from the optical axis than the point 93, whichcorresponds to the front-toback magnification which was herein desired.However, in a direction or plane at right angles, the cross-section ofthe lens is merely an elongated rectangle, and consequently thecylindrical lens in this direction acts only as a parallel plateandproduces no magnification. The result of this type of lens arrangementis that the image along all lines which are parallel to the line or sideAB is unmagnified and undistorted.

in a modification of the invention, as shown by Fig. 6, an arrangementfor reversing the image compression is schematically shown. In thisfigure, the image dl radiates light, which is reflected by thecylindrical concave mirror 78, which is mounted in the lid is oi thecabinet member til. The axial distance of the image ll from the mirrorit must be less than the focal length of the mirror in that plane. Thelid construction is preferably of the same general form, except for theconcave feature, as shown by the Zworykin patent above mentioned. Theconcave mirror or reflecting surface 18 is arranged to be tilted aboutits back edge, in directions shown and conventionally indicated by thearrows 16 and 17, so as to be brought into a convenient position to beviewed by the observer or locker, conventionally represented at 15.

The remaining portion of the cabinet construction embodies the videoreceiver and synchronizing circuits, together with any desired soundreproducing apparatus, as disclosed by the above mentioned Zworykinpatent. If new, for instance, the screen picture M is closer to themirror 18 than the focal length of the mirror in that plane of itsconcavity, a virtual image will be produced thereby and this virtualimage will be enlarged only from front to back, but not from left toright. Accordingly, by suitably selecting the radius of curvaturev ofthe mirror 18, the requisite degree of front-to-back expansion of thepicture produced in the area ll of the tube l4 may be accomplished.

In the arrangement disclosed by Fig. 6, the receiving instrumentalityhas been shown only in a conventional manner and preferably embodies thegeneral feature disclosed by the Carlson Reissue Patent No. 20,700 abovenamed.

In further modifications of the invention, it is also possible tocombine the general methods concave cylindrical mirror further removedtherefrom, the combination of these optical elements for producing thedesired change in the aspect ratio of the picture may be provided. Undersuch circumstances, the optical elements in the case may be weaker orless powerful than with the use of individual lens and/or reflectingelements.

In a modified form, the foregoing invention is particularly applicableto the production of large size images by virtue of optical enlargingsystems. Essentially, the optical enlarging systems comprise amultiplicity of spaced positive lens elements whose powers progressivelyand suitably decrease and-whose apertures progressively'andappropriately increase in relation to the separation of the lenselements from the object or image as itis produced upon the end of thecathode ray viewing tube. v

Referring nowparticularly to Fig. 7, there is disclosed an opticalsystem for use in connection with the production of anamorphotictelevision images. The disclosed optical system will serve store suchpictures or images to normal aspect ratios. The system of Fig. 7 isbroadly intended to accomplish two results, of which the first is toenlarge the image area upon the end of the cathode ray tube beyond itsoriginal size as it is viewed, and, at the same time, the optical systemserves to restore such pictures to their original and usual aspectratio.

The optical arrangement disclosed by Figs. 7a and 7b can be assumed, forexample, as one by which the original image was 4.2" x 6.8", with theresultant enlarged image of 7.38" by 9.75". The original image. with thesystem as disclosed by Figs. 7a and 7b is assumed to be producedwith'anaspect ratio of 1.62 and restored in enlarged form to an imagehaving an aspect ratio of 1.33, as is customarily used. I

Now referring particularly to Fig. 7a thereof, there is disclosed across-section of the enlarging system considered in a plane through thecenter of the original television picture andparallel to its, height.The related drawing, namely Fig. 7b, .is a cross-section of the opticalsystem in a plane through the center of the original picture andparallel to the width thereof. In each part of Fig. 7 there isillustrated one lens system and dimensions which have proven practical.The

, illustrated lens system arrangement is to be'understood as beingdescriptive of one suitable system, although some slight modificationsmight use of a. shallower tube than is customarily adopted for morenormal aspect ratios. The light rays from the television picture firstpass through lens A. The lens A is a cylindrical lens with itscylindrical axis perpendicular to the plane of the for the enlargementof such pictures and will rein any way departing from the spirit of theinpaper of the drawing in Fig. 7a, but parallel thereto in Fig. 7b.

The aperture I02, I22 of the lens A in the direction of the drawing Fig.7a is assumed. as being 7.8". The focal length of the cylindrical lens.A, which is positive, is 15.. One face of the lens is plane and theother has a radius of cylindrical curvature of 8", the index ofrefraction being 1.523. The thickness of the lens at its center is 1.0.

After light rays pass through the lens A, the light bundle I29, I30 isbounded, in the plane of the paper, between the rays I33, I34, which aredirected backward to the first enlarged image at I01 and indicatedbetween the points 3 and H4. This image need not be further consideredat the present time for an understanding of the application, however,because the light bundle then strikes the cylindrical-spherical lens B,of which the planar aspect of the cylindrical component is schematicallyrepresented between the points I5I, I04 and I49 in-Fig. 7a, and on whichthe spherical portion is shown between the points I52, I05 and I50.The-focal length of the spherical portion is 104", with a radius ofcurvature of 54", with the index of refraction of the glass also being1.523 and the thickness of the lens which, for the purposes ofillustration, can be considered as the height of the normal pictureproduced on the luminescent end .target of the usual 12" cathode raytube.

In the showing of Fig. 7a, a plane mirror I59, I60 is indicated as beinglocated in the path of the emergent light rays. This is shown solely forpurposes of indicating convenience in viewing the resultant picture inthe general manner suggested by Zworykin Patent No. 1,870,702.Furthermore, it should be understood, in connection with the showing ofFig. 7a, that while the mirror surface I59, I60 is indicated as havingbeen placed beyond the lens B, it is to be understood that the opticalsystem might readily be modified so as to locate the mirror intermediatethe lens elements A and B Without which are represented at the points H9and I20,

may be considered as embodying the hereinabove suggested dimensions of6.8". In this showing, the planar aspect of the cylindrical lens A isset forth, and it may be pointed out that its clear aperture in theplane of the paper is 11.

The cross-section of the lens B shows at its left the cylindricalcomponent in cross-section. The lens in. this direction has a focallength of 63 and a radius of curvature of 33", with the 6 glass indexagain being 1523", above noted. The right hand surface of the lens B, inFig. 7b,

as is represented between the points I28, I and Ill, is a sphericalcross-section, as hereinabove described. The clear aperture of lens B inthe plane of the paper is, as shown in the drawings, The other twodimensions of the reflectin mirror "8,". are shown at Iii and I62, whichis the mirror shown by Fig. 7a, projected upon the plane of the paper,and point I65 represents a point thereon from which the light :ray I58passes perpendicularly from the plane of the paper, assuming the mirrorI59, I60, I62, Iii to be inclined at an assumed angle of 45 degrees tothe optical axis of the system (see particularly Fig. 7a).

Considering Fig. 7b still further, it will be noted that this opticalsystem provides for enlarging an original picture of the sizehereinabove suggested. The length dimension of the enlarged virtualimage first produced by the lens A is represented only between thepoints IIS and I IE; but the length dimension of the second or finalvirtual image produced by the combination of the lenses A and B isrepresented between the points III and III. The light rays indicated atIll and I32, which pass from the object area IIlI to the lens A,correspond functionally to the light rays I29 and I30 of Fig. 7a;similarly, the light rays I and I36 and I3! and Ill! correspondfunctionally or associatively respectively to the rays I33 and I34 andI31 and I38 of Fig. 7a.

From the foregoing it will be apparent that the system herein describedis utilized in combination with television image reproducing tubes andprovides for enlarging the developed image in one direction only toproduce a desired aspect ratio, or where desired, the image may beenlarged in two directions with the degree of enlargement ormagnification diflerent in each direction so that the desired aspectratio, of the viewed image is realizable.

In the foregoing description it has been as-' sumed for purpose ofillustration that the original image is produced on a viewing or targetarea which is planar in nature. However, in practice, and especially inthe manufacture of cathode ray tubes for use in television imagereproducers, the end surface. of the cathode ray tube upon whichthe'image is caused to appear is usually curved so that it is convextoward an observer or toward the lens system of the magnifier.Accordingly, in order to compensate for this curvature some slightmodifications in the dimensions of the described optical system may bemade in practice. However, such slight changes will not introduce anynew distortions, and the convex surfacelacing toward the lens system issuch that the distortion of the magnified image, as viewed, is actuallyless than if the image were formed upon a planar surface. This lsbecause of the fact that the so-called pin-cushion distortion of theimage which exists to some slight extent in such a magnifier system isreduced by the convexity of the original image toward the magnifyinglens and optical system. Furthermore, with regard to the permissibleangle of, viewing the image as it is magnified, the foreshortening ofthe obliquely viewed image is no greater when tions in the opticalsystem than would be possible in the case of the planar image.

In the specific example of one form of optical system which hashereinbeen set forth it will be understood that the optical system issubstantially corrected for spherical aberration and distortion, such asbarrel" and pin-cushion" effects, but not to any substantial extent forchromatic aberration or coma, which'are each negligible in obtainlng thedegree of enlargement herein suggested. However. minor modifications indesign will provide such correction where it becomes necessary due toincreased enlargement or for other reasons.

It will, of course, be obvious that many and various modifications inthe system may be made without departing from the spirit or scope of theinvention as ltisherein set forth and claimed.

What I claim is:

V 1. A television picture enlarger comprising an object area having anaspect ratio changed from normalsize and an anamorphic optical meanscooperatively associated with said tube for expanding said image in onedimension only for viewing.

3. In a television system, a cathode ray image reproducing tube having aviewing target area,

means toproduce on the target area an electrooptical bidimensional imagehaving at least one division thereof reduced from normal viewingproportion relative to the other dimension and an anamorphic opticalmeans cooperatively as sociated with said tube for enlarging said imageby e panding said image in one of said directions to a greater degreethan in the other direction to produce a viewed image of predeterminedaspect ratio.

4. A television picture enlarger comprising a I target area and means toproduce thereon an electro-optical image area having at least one di-.mension thereof changed from normal viewing size and an anamorphicoptical'means cooperatively associated with said image area forenlarging said produced image by expanding said image during enlargementin one direction greater than in another direction.

5. In a television system, an electron tube for producing abidimensional electro-optical image,

means for distorting the image in its production in one of its twodirections only, and at least one anamorphic optical means positionedsubstantially adjacent the produced image for distorting the developedimage in a sense opposite to that of first distortion. Y

6. In a television system, an electron tube for producing a.bidimensional electro-optical image, means for reducing the size of theproduced image relative to normal viewing size in its production in oneof its two directions only, and an anamorphicoptical means positionedadjacent the produced image for enlarging the developed image in a senseopposite to that of first distortion.

-7. A television system comprising a cathode ray tube having aluminescent target area, means somewhat better correction of imageaberrae cal pattern compressed in one dimension, and an for producing anelectro-optical bidimensional image upon the said target area,electrical means for distorting the image in its production in one ofits two dimensions, a light reflecting element adapted to be positionedat an angle of the order of 45 degrees to the plane of the luminescenttarget for viewingthe produced image, and an anamorphic lens elementinterposed between the reflecting member and the luminescent target fordistorting the produced electro-optical image in a sense opposite tothat of its distortion in production so that an observer views the imagein predetermined normal proportions.

8. A television system comprising a cathode ray tube having aluminescent target area, means for producing an electro-opticalbidimensional image upon the said target area, electro-magnetic meansfor distorting the image in its production in one of its two dimensions,a light reflecting element adapted to be positioned at an angle of theorder of 45 degrees to the plane of the luminescent target for viewingthe produced image, and an anamorphic lens element interposed betweenthe reflecting member and the luminescent target for distorting theproduced electro-optical image in a sense opposite to thatof' itsdistortion in production so that an observer views the image in normalproportions.

9. A television system comprising a cathode ray tube having aluminescent target area, means for producing an electro-opticalbidimensional image upon the said target area, electrical means fordistorting the image in its production inone of its two dimensions, alight reflecting element adapted to be positioned at an angle ofthe'order of 45 degrees to the plane of the luminescent target forviewing the produced image, and an anamorphic lens element interposedbetween the reflecting member and the luminescent target for distortingthe produced electro-optical image in a sense opposite to that of itsdistortion in production so that an observer views the image in normalproportions.

'10. A television system comprising a cathode ray tube having aluminescent target area, means for producing an electro-opticalbidimensional image upon the said target area, 'electro-static means fordistorting the image in its production anamorphic optical means forexpanding the produced image in its direction of distortion to produce avirtual image of the initial image of predetermined aspect ratio forviewing.

12. In a television system, a cathode ray tube having included thereinmeans to develop an electron beam and a target area upon which thedeveloped beam is adapted to impinge to produce luminous effects, meansresponsive to received signals to control the intensity of the producedelectron beam whereby the intensity of the resuiting luminous effects isvaried so that an electro-optical image representation results upon theluminescent target, deflecting means for causing the produced beam totraverse the target in bidimensional patterns, electrode means torestrict the area of beam impact upon the targetto' one of substantiallyelliptical dimensions, said ellipse having its major axis dimensioncorresponding substantially to the normal height of one picture line andits minor axis representing a compression in image production wherebythere results upon the tube target an electro-opticai pattern compressedin one of its two dimensions, and an anamorphic optical means forexpanding the produced image in its direction of compression to producea virtual image of the initial image of predetermined aspect ratio.

- 13. In a television system, afcathode ray tube having included thereinmeans to develop a'n electron beam and a target area upon which thedeveloped beam is adapted to impinge to produce luminous effects, meansresponsive to received signals to control the intensity of the electronbeam whereby the intensity of the luminous eflects produced is so variedthat an electrooptical image representation results upon the luminescenttarget, means for causing the proan electro-optical pattern compressedin one of in one of its two dimensions, a light reflecting elementadapted to be positioned at an angle of the order of degrees to theplane of the luminescent target for viewing the produced image, and ananamorphic lens element interposed between the reflecting member and theluminescent target for distorting the produced electro-optical image ina sense opposite to that oil its distortion in production so that anobserver views the image in normal proportions.

11. In a television system, a cathode ray tube having included thereinmeans to develop an electron beam and a target area upon which thedeveloped beam is adapted to impinge to produce luminous effects, meansto control the intensity of the electron beam whereby the intensity ofthe luminous effects is varied so that an electro-opti- I cal imagerepresentation results upon the luminescent target,'deflecting means forcausing the produced beam to traverse the target in bidimensionalpatterns, means to restrict the area of beam impact upon the target toone of substantially elliptical dimensions with the major axis of theellipse corresponding substantially to the normal height or one pictureline and the minor axis of the ellipse representing a compression inimage production whereby there results an electro-optienlarged image oi.the television picture area, at

its two dimensions, an anamorphic optical system for enlarging theproduced image in each direction and expanding the enlargement in thedirection of initial compression to a degree greater than in the otherdirection to produce a virtual image of the initial image of predetermined aspect ratio, and reflector means in which to view theproducedvirtualimage.

14. In a television system, a cathode ray tube for producing anelectro-optical television image,

means for compressing the television image produced in one directiononly to produce an image having an aspect ratio substantially less thana predetermined normal aspect ratio, a multiplicity of spaced positiveoptical image-forming elements of progressively decreasing powers andprogres sively increasing apertures in relation to their spacing fromthe tube to form a virtual and for-producing an electro-opticaltelevision image,

means for compressing the television image produced in one directiononly to produce an image having an aspect ratio substantially less thana predetermined normal aspect ratio, a multiplicity of spaced positiveoptical image-forming elements of progressively decreasing powers andprogressively increasing apertures in relation to their spacing from thetubeto form a virtual and enlarged image of the television picture area,

' at least one of said optical image-forming elements being adapted toexpand' the produced optical image in one direction to converttheproduced picture oi less than normal aspect ratio into one ofpredetermined increased aspect ratio for viewing by an observer, and areflecting element interposed between the image pro-' ducing tube andthe observer, said reflector being inclined at substantially a 45 degreeangle to the optical path of the image initially produced.

16. A television receiver system comprising a cathode ray tube havingmeans included therein ior producing an electro-optical image having apredetermined aspect ratio between image height and image width, anoptical system for enlarging the said image comprising a plurality ofpositive sphere-cylindrical and cylindrical lenses each separated onefrom the other by distances substantially less than their respectivefocal lengths, said lenses having progressively diminishing power andprogressively increasing aperture in relation to their separation fromthe image area on the tube so as to form an enlarged erect verticalimage of the electro-optical image produced upon the tube and to expandthe enlarged image in one direction of width and height greater than inthe other direction of width and height so as to transform the produoedelectro-optical image into a vertical image having an aspect ratiodiflerent from that initially produced.-

17. A television system comprising a cathode ray tube having aluminescent target and means to produce -uponsaid target aneiectro-optical bidimensional image having a predetermined distortion inone of its two directions, in combination with an. anamorphic lightreflecting element adapted to be positioned at a predeter-' in saidreflector views an image of substantially normal proportions in each ofits dimensions.

18. A television picture enlarger for enlarging a real image developedupon the luminiscent targetoi! a cathode ray tube in a manner such thatthe real image is compressed in one direction only from its normaldimensions so as to provide an image having an aspect ratio substantially of a value other than a predetermined normal ratio, whichcomprises a multiplicity of spaced positive optical image-formingelements of progressively decreasing powers and progressively increasingapertures in relation to their separation from the real image producingarea to iorm a virtual and enlarged image of said area, at least one ofsaid optical elements having anamorphic properties for expanding thesaid observed image in one of said directions to an amount greater thanthe expansion in a direction normal thereto so as to convert theproreflecting element located intermediate the said two mutuallyperpendicular lens elements and in a plane at approximately relative tothe optical axis of each of said lens elements.

ALFRED N. G-QLDSll/HTH.

